[U-Boot] DWMMC crontroller in Exynos4412

Przemyslaw Marczak
2015-08-26T14:12:26Z

Hi Humberto,

On 08/26/2015 03:40 PM, Humberto L?pez Le?n wrote:
> Hi community,
>
> thank you all for answering my questions.
>
> On 08/26/2015 02:53 AM, Przemyslaw Marczak wrote:
>> Hi,
>>
>> On 08/26/2015 08:23 AM, Jaehoon Chung wrote:
>>> On 08/26/2015 11:26 AM, Simon Glass wrote:
>>>> +Samsung people
>>>>
>>>> Hi,
>>>>
>>>> On 25 August 2015 at 13:10, Humberto L?pez Le?n <humberto@uclv.cu>
>>>> wrote:
>>>>> Hi Simon,
>>>>> I'm working on implementing a driver for SD/MMC cards in the framework
>>>>> GenodeOS. I think you could help me with your experience in this
>>>>> type of
>>>>> implementation in the u-boot.
>>>>> The hardware platform on which the driver will work is a ODROID-x2
>>>>> (exynos4412). I use the DWMMC contoller, but I'm not sure if this
>>>>> is the
>>>>> right controller to handle SD/MMC cards in Exynos4412 SoC. The SDHCI
>>>>> controller is most appropriate?
>>>
>>> If you're using exynos4412 board, you can choose sdhci or dwmmc
>>> controller for eMMC, not SD/SDIO.
>>> And in my experiment, dwmmc controller is more appropriate than
>>> sdhci.(ex, performance)
>>>
>>
>> It depends which mmc channel is used. In Exynos4412, there are 5
>> channels, but some channel configurations shares GPIO pins:
>> - MMC0 - sdhci
>> - MMC1 - sdhci, or MMC0 8-bit
>> - MMC2 - sdhci - Odroid SD card, 4-bit mode
>> - MMC3 - sdhci - or MMC2 8-bit
>> - MMC4 - dwmmc, uses MMC0 pins for 4-bit, and MMC0-1 for 8-bit mode
>>
>> Odroid is using MMC2(sdhci) and MMC0/4(sdhci or dwmmc).
>>
>> So for eMMC cards you can use the dwmmc, and as Jaehoon wrote it is
>> recommended for the better performance, but for SD card you must use
>> sdhci controller.
> This information is valuable to me, but now I would help if you tell me
> where I can find the code of SDHCI controller for the SD card of
> Exynos4412 in U-boat 2015.04-rc2 for a implementationtation reference. I
> was reviewing the file exynos_dw_mmc.c as reference of DWMMC driver,
> but now I have no idea what the file where the SDHCI driver for the
> exynos4412 is implemented.
>
> Thank you very much for your collaboration.
>
>
>

Please check those files:
- drivers/mmc/s5p_sdhci.c
- drivers/mmc/sdhci.c

But, isn't the kernel a better reference for you?

Best regards,
--
Przemyslaw Marczak
Samsung R&D Institute Poland
Samsung Electronics
p.marczak at samsung.com